BANGKOK, Thailand -- Bolstered by an endorsement from Thailand's king, the nation's new military ruler issued a stark warning Monday to anyone opposed to last week's coup: don't cause trouble, don't criticize, don't protest -- or else the nation could revert to the "old days" of turmoil and street violence.

Speaking in his first public appearance since the coup, Gen. Prayuth Chan-ocha defended the army's takeover, saying he had to restore order after seven months of increasingly violent confrontations between the now-ousted government and demonstrators who had long urged the army to intervene.

"I'm not here to argue with anyone. I want to bring everything out in the open and fix it," said Prayuth, who spoke at the army headquarters in Bangkok dressed in a crisp white military uniform.

"Everyone must help me," he said, adding: but "do not criticize, do not create new problems. It's no use."

The tough words came as an aide to former Prime Minister Yingluck Shinawatra said she had been released Monday from military custody after being held for three days at an undisclosed location without access to a telephone. The aide, who spoke on condition of anonymity because of the sensitivity of the situation, said Yingluck had returned to her home.

In a gruff, 20-minute appearance, Prayuth warned the media and social media users to avoid doing anything that could fan the conflict. He also called on anti-coup protesters who have been staging small-scale demonstrations to stop.

"Right now there are people coming out to protest. So do you want to go back to the old days? I'm asking the people in the country, if you want it that way, then I will have to enforce the law."

Earlier Monday, a royal command sent in the name of King Bhumibol Adulyadej officially endorsed Prayuth to run the country and called for "reconciliation among the people."

Bhumibol, who is 86 and in fragile health, did not attend the ceremony, in which Prayuth knelt down before a large picture of the monarch and offered a decorated cone of banana leaves. The endorsement is a formality, but an important one in such circumstances as contending political forces look for signs that the king may not be approving such actions. But Monday's ceremony offered no such clues, dampening any speculation that the palace might withhold its support for the junta.

Thursday's coup, Thailand's second in eight years, deposed an elected government that had insisted for months that the nation's fragile democracy was under attack from protesters, the courts, and finally the army.

The country is deeply split between an elite establishment based in Bangkok and the south that cannot win elections on one side, and a poorer majority in the north that has begun to realize political and economic power on the other.

Despite the threat to crack down on anti-coup protesters, soldiers did not use force against several hundred people who gathered again Monday at the city's Victory Monument and eventually dispersed on their own, vowing to return Tuesday.

"Freedom is more important, isn't it?" said Khao Thitipong. "If we don't have freedom, we don't have life."

Through a loudspeaker, a soldier taunted the protesters, saying they had been paid to come out. "Can you still call yourselves patriots?" he said.

The soldier also accused international journalists at the scene of inciting the conflict. "Do you think they are good for Thailand?" he said, before addressing them directly in English: "Foreign media, be careful."

Prayuth defended the takeover, saying that "when the conflict intensified, and there was the threat of violence, we had to act."

"We are not doing this for the soldiers. I'm doing this to protect the honour and dignity of all Thais. We cannot step back anymore. We have to stop arguing," he said. "The most important thing right now is to keep peace and order in the country."

Since sporadic violence began last November as anti-government protests gathered steam, at least 28 people have been killed and more than 800 injured in grenade attacks, gun fights and drive-by shootings.

After declaring martial law May 20, Prayuth invited political rivals and Cabinet ministers for two days of peace talks to resolve the crisis. But those talks lasted just four hours. At the end of the meeting, Prayuth ordered everyone inside detained, and announced the coup on state television almost immediately afterward.

The junta has ordered more than 200 people -- including most of the ousted government -- to report to the authorities. They include scholars, journalists and political activists seen as critical of the regime. Some have been released, but an unknown number remain in custody. Other activists have fled or are in hiding, and human rights groups describe a chilling atmosphere with soldiers visiting the homes of perceived critics and taking them away.

Prayuth said the army was taking people into custody to give them time "to calm themselves down" and none was being tortured or beaten.

"When summoned, they will be asked about what they've done. ... If they are calm and still, they will be released, in three days, five days, seven days," Prayuth said.

On Monday, the army released ex-lawmaker Suthep Thaugsuban, who led half a year of demonstrations against the deposed government.

Suthep was escorted to the criminal court by security officers and formally charged with murder for giving the army orders to crack down on protesters in 2010 when he was serving as deputy prime minister. But he was immediately released on bail and grinned broadly as walked out of the courthouse.

There has been no armed resistance to the coup, but a soldier was fatally shot Monday in the eastern province of Trat, where three people were killed in February in a drive-by shooting and grenade attack on a protest rally against the former government. Police Maj. Gen. Thisathat Buranarat said about 40 soldiers who surrounded a house containing suspects linked to the attack exchanged gunfire with them, and one of the three inside escaped.

The operation followed a raid last week on a house in Bangkok's western outskirts that found a cache of weapons matching those used in the February attack.

The junta has yet to map a way out of the crisis, but Prayuth said there would be political and administrative reforms. On Monday, he gave the green light for the Finance Ministry to seek billions of dollars in loans to pay debts owed farmers under a disastrous rice scheme instituted by the ousted government.

After the speech, the general took only two questions from reporters.

Asked if he would appoint a new prime minister, Prayuth replied gruffly: "Don't ask about something that hasn't happened. It's already in the plans. Take it easy. There will be one."

Asked when elections would be held, Prayuth said that could happen when the crisis ends. It "depends on the circumstances," he said. "I don't have a schedule ... quickly as possible."